The arthropod community of boreal Norway spruce forests responds variably to stump harvesting

Abstract

Forest fuel harvesting increases the need to collect not just logging residues but also tree stumps from harvested stands. This biomass removal has raised concern over forest biodiversity. Here, the effects of stump harvesting on spiders, ants, harvestmen, ground beetles and epiedaphic springtails occupying boreal Norway spruce (Picea abies) forest floor were studied two and five years after harvesting by comparing pitfall trap samples from clear-cut sites with and without subsequent stump harvesting and from unharvested mature forests in central Finland. At harvested sites, traps were placed both on intact and exposed mineral soil surface. Open-habitat and generalist ground beetles benefitted from the stump harvesting, but generally the numbers of arthropods between stump harvesting treatments and different aged clear-cuts were rather similar. The intact forest floor hosted more ants, springtails and harvestmen than did the exposed mineral soil. Moreover, the community structure of spiders, ground beetles and springtails was affected by stump harvesting, forest-floor quality (intact or exposed), and time elapsed since harvesting. Based on these results we recommend minimizing the exposure of mineral soil during management practices. However, more long-term studies are required to document the development of fauna in the harvested areas and the ecosystem-level impacts of utilization of forest biomass for energy.